Characterization of several classes of second-order ODEs by using differential invariants.
Chasse au canard. Ie partie.
Chemotaxis models with a threshold cell density
We consider a quasilinear parabolic system which has the structure of Patlak-Keller-Segel model of chemotaxis and contains a class of models with degenerate diffusion. A cell population is described in terms of volume fraction or density. In the latter case, it is assumed that there is a threshold value which the density of cells cannot exceed. Existence and uniqueness of solutions to the corresponding initial-boundary value problem and existence of space inhomogeneous stationary solutions are discussed....
Chordal cubic systems.
We classify the phase portraits of the cubic systems in the plane such that they do not have finite critical points, and the critical points on the equator of the Poincaré sphere are isolated and have linear part non-identically zero.
Classification and existence of positive solutions to nonlinear dynamic equations on time scales.
Classification des solutions d’un problème elliptique fortement non linéaire
On étudie la classification des solutions du problème elliptiqueoù et une fonction changeant de signe. En utilisant une méthode de tire, On montre qu’en partant avec une dérivée initiale nulle toutes les solutions sont globales. De plus si et l’ensemble des solutions est constitué d’une seule solution à support compact et de deux familles de solutions ; celles qui sont strictement positives et celles qui changent de signes. On montre aussi que ces deux familles tendent vers l’infini quand...
Classifications and existence of nonoscillatory solutions of second order nonlinear neutral differential equations
A class of neutral nonlinear differential equations is studied. Various classifications of their eventually positive solutions are given. Necessary and/or sufficient conditions are then derived for the existence of these eventually positive solutions. The derivations are based on two fixed point theorems as well as the method of successive approximations.
Coefficients of prolongations for symmetries of ODEs.
Coexistence of singular and regular solutions for the equation of Chipot and Weissler.
Coexistence of small and large amplitude limit cycles of polynomial differential systems of degree four
A class of degree four differential systems that have an invariant conic , , is examined. We show the coexistence of small amplitude limit cycles, large amplitude limit cycles, and invariant algebraic curves under perturbations of the coefficients of the systems.
Cohomology and Morse theory for strongly indefinite functionals.
Comments on “A new method for the explicit integration of Lotka-Volterra equations”.
Common increasing dispersions of certain linear second order differential equations
Commutators and linearizations of isochronous centers
We study isochronous centers of some classes of plane differential systems. We consider systems with constant angular speed, both with homogeneous and nonhomogenous nonlinearities. We show how to construct linearizations and first integrals of such systems, if a commutator is known. Commutators are found for some classes of systems. The results obtained are used to prove the isochronicity of some classes of centers, and to find first integrals for a class of Liénard equations with isochronous centers....
Compactness condition for boundary value problems
Comparison and oscillation theorems for second order differential equations
Comparison results for impulsive delay differential inequalities and equations.
Comparison results for two-dimensional half-linear cyclic differential systems
Two identities of the Picone type for a class of half-linear differential systems in the plane are established and the Sturmian comparison theory for such systems is developed with the help of these new formulas.
Comparison theorem for third-order differential equations
Comparison theorems for differential equations with deviating argument